The present invention relates to the field of hand operable sanding devices. More particularly, the present invention relates to an easily gripped handle that can be affixed to an existing palm sander device that reduces cumulative hand and wrist trauma.
Sanding is an abrasive process that requires that two surfaces rub together and is extremely time consuming and tedious when performed manually. Various power-driven sanders have been available for some time and frequently require the use of two hands due to excessive weight. Belt sanders are one type of hand sander that is available but these are generally used for roughly removing large amounts of material. Belt sanders themselves are heavy and are not recommended for one-handed operation. Two handed sanders have limited usefulness on vertical and overhead surfaces because of their size and weight.
Sanders that can be operated with one hand include oscillating and random orbit palm sanders. Random orbit palm sanders are pneumatically powered and typically have a small power head with a trigger paddle attached to the top. On the bottom of the random orbit palm sander is a small, typically about six-inch diameter, sanding disc that is fixed to a spinning pad. A random orbit action is achieved by use of an eccentric weight or cam in the drive which causes the pad to orbit a center point while spinning at a high speed with respect to the power head. The random orbit pattern is necessary to produce a mechanical action that results in a swirl free finish. However, the random oscillation transfers considerable vibration to the operator""s hand and the operator must grip the power head tightly with his or her fingers to both control the action and maintain palm pressure on the trigger paddle. Oscillating sanders are generally less effective in producing a swirl-free surface and are therefore not as desirable in many applications.
Regardless of the type, oscillating, random orbit or other, all power hand sanders produce some vibration. Operators cannot be completely isolated from vibration because the operator must apply pressure to some degree in order for the sanding disc to remove material from the surface being sanded. Heavier sanders aid in pressure application but, as mentioned above, they are limited to use in vertical and overhead surfaces.
One industry that requires a significant amount of sanding labor is the aerospace industry. Sanding is typically required on both the aluminum fuselages and on composite control surfaces and panels of aircraft before the application of paint or for the removal of old paint in a paint hanger. Because of the nature of the fuselage and its surface shapes, one-handed control of the sander and use of the sander on vertical surfaces and overhead surfaces is necessary. The tight grip required to use the sanders in a paint hanger can reduce blood flow to the fingers and result in musculoskeletal stress that is further exacerbated by vibration. In addition, when sanding a vertical or overhead surface in a fuselage, the operator""s wrist is typically extended which results in greater musculoskeletal stress. Prolonged exposure to these conditions can lead to Raynaud""s disease and/or carpal tunnel syndrome. Raynaud""s disease is commonly called xe2x80x9cwhite fingerxe2x80x9d and results in numbness, cold skin and a blue color when exposed to cold temperatures. Raynaud""s disease can be a permanent condition. Carpal tunnel syndrome is an inflammation of the flexor tendons of the fingers which pass through a channel on the palmer side of the wrist formed by the carpal bones and the transverse carpal ligament. These flexor tendons become inflamed with repetitive overuse and place pressure on the nearby median nerve. Pressure on the median nerve causes numbness and/or pain in the lower arm. Carpal tunnel syndrome can also result in permanent dysfunction.
Small oscillating detail sanders solve some of the repetitive motion problems by having a very short stroke at a very high frequency with a low weight. This greatly reduces vibration that is transmitted to the hand of the operator. However, the area and mass of the sanding pad must be kept too small to be of any practical value on large surfaces, such as those encountered when sanding an aircraft fuselage. Automated sanding machines have been used on fuselages, but oftentimes fail to reliably negotiate vertical and overhead surfaces.
Therefore, it would be advantageous to have an operable sanding device that is easily gripped with one hand or both hands and can be used to negotiate large sanding surfaces. In addition, it would be advantageous to have a sanding device that is light in weight and transmits minimal vibrations to reduce the incidence of cumulative trauma to the hand and wrist of the operator.
The present invention includes an ergonomic sander handle for a sanding device that reduces the incidence of cumulative trauma to the hand of a worker using the sanding device. The sander handle provides an ergonomic grip by having an elongated tubular body attached to the sanding device at one end and a bearing at the other end. The handle can be gripped by the worker with a single hand in an anatomically friendly position without flexion or deviation of the hand and wrist. In addition, the ergonomic handle is of light-weight construction to reduce loads on the hand and wrist of the operator when sanding vertical and overhead surfaces, such as the fuselage of an airplane.
In one aspect of the invention, an ergonomic handle for clamping onto a sanding device so that the ergonomic handle can be gripped by a worker and used to apply the sanding device to a surface, is disclosed. The ergonomic handle includes an elongate body, a clamp head and a bearing. The elongate body has a head end and an opposing tail end. The clamp head is attached to the head end of the elongate body and is operable to clamp the sanding device. The bearing is attached to the tail end of the elongate body, opposite the clamp head. In use, the worker clamps the clamp head onto the sanding device, grips the elongate body, applies the sanding device and bearing to the surface and moves the sanding device and bearing along the surface during sanding.
In another aspect of the invention, an ergonomic sander that can be gripped by a worker and used to sand a surface, is disclosed. The ergonomic sander includes an elongate body, a sanding head and a bearing. The elongate body has a head end and an opposing tail end. The ergonomic sander also includes a sanding head that is attached to the head end of the elongate body and has a sanding interface operable to sand the surface. The bearing is attached to the tail end of the elongate body, opposite the sanding head. In use, the worker clamps the clamp head onto the sanding device, grips the elongate body, applies the sanding device and bearing to the surface and moves the sanding device and bearing along the surface during sanding.
The bearing can include a fluoropolymer resin pad (e.g., a Teflon(copyright) material) or a pair of freely rotating roller balls. The bearing can include a hinge that allows it to pivot with respect to the tail end of the elongate body. The bearing can also include a height-adjustable bracket mounted to the tail end of the elongate body and operable to adjust the height of the handle with respect to the bearing. The bearing serves as a support for the elongate body that allows the downward application of pressure on the elongate body with a power grip. Changing the bearing height and the bearing""s ability to pivot on the hinge allows the bearing to adjust to various non-planar surfaces. The bearing can also include an air bearing which comprises a plurality of holes in the resin pad. Air bled from the exhaust of the sanding device or air supply line is fed through plumbing and the holes in the resin pad to reduce friction between the resin pad and the surface being sanded.
The elongate body can have a tubular shape covered with padding to reduce grip fatigue. A trigger may also be included that is operable to control power to the sanding device. The trigger has an elongated paddle shape that is attached to the clamp head and extends along the elongate body. The trigger can be attached to the clamp head using a pivot pin that allows the trigger to pivot when grasped. The trigger may also include an adjustment bolt positioned to contact a power switch on the sanding device. The adjustment bolt is adjustable to change the angular orientation of the trigger with respect to the elongate body. Alternatively, the trigger could be attached directly to the sanding head. The paddle shape allows the trigger to be grasped from several positions along the elongate body. Changing the orientation of the trigger allows for adjustment to suit different hand sizes and finger lengths.
The clamp head typically includes a pair of jaws connected by a jaw pin. The pair of jaws are operable to clamp the sanding device by at least partially encircling the sanding device. The pair of jaws may also include a draw bolt inserted through each jaw of the pair of jaws. Tightening of the draw bolt draws the jaws together in a pinching motion. The clamp head can also include a pivot mount in which the head end of the elongate body is free to slide and pivot. The pivot mount includes a slot and the head end of the body includes a ball mounted in the slot for sliding and pivoting therein.
The sander handle of the present invention reduces the risk of injury due to vibration and poor grip posture by allowing a random orbit sanding device to be held and controlled in a power grip. In the power grip the wrist is held in a neutral position, or slightly extended. The power grip allows good blood flow to the hand and fingers, reducing the incidence of Raynaud""s disease and carpal tunnel syndrome. The ergonomic handle can be held securely overhead with the fingers relaxed. In addition, the ergonomic handle separates the forces required to control sanding direction and pressure from the more precision forces required to control the trigger. As a result, the operator can put more force on the sanding interface with less hand and wrist fatigue while still maintaining control using only one hand.